/*------------------------------------------
   RANDRECT.C -- Displays Random Rectangles
                 (c) Charles Petzold, 1998
  ------------------------------------------*/

#include <windows.h>
#include <stdlib.h>           // for the rand function

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;
void DrawRectangle (HWND) ;

int cxClient, cyClient ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
	PSTR szCmdLine, int iCmdShow)
{
	static TCHAR szAppName[] = TEXT ("RandRect") ;
	HWND         hwnd ;
	MSG          msg ;
	WNDCLASS     wndclass ;

	wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
	wndclass.lpfnWndProc   = WndProc ;
	wndclass.cbClsExtra    = 0 ;
	wndclass.cbWndExtra    = 0 ;
	wndclass.hInstance     = hInstance ;
	wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
	wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
	wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
	wndclass.lpszMenuName  = NULL ;
	wndclass.lpszClassName = szAppName ;

	if (!RegisterClass (&wndclass))
	{
		MessageBox (NULL, TEXT ("This program requires Windows NT!"),
			szAppName, MB_ICONERROR) ;
		return 0 ;
	}

	hwnd = CreateWindow (szAppName, TEXT ("Random Rectangles"),
		WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, CW_USEDEFAULT,
		CW_USEDEFAULT, CW_USEDEFAULT,
		NULL, NULL, hInstance, NULL) ;

	ShowWindow (hwnd, iCmdShow) ;
	UpdateWindow (hwnd) ;

	while (TRUE)
	{
		if (PeekMessage (&msg, NULL, 0, 0, PM_REMOVE))
		{
			if (msg.message == WM_QUIT)
				break ;

			TranslateMessage (&msg) ;
			DispatchMessage (&msg) ;
		}
		else
			DrawRectangle (hwnd) ;
	}
	return msg.wParam ;
}

LRESULT CALLBACK WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
{
	switch (iMsg)
	{
	case WM_SIZE:
		cxClient = LOWORD (lParam) ;
		cyClient = HIWORD (lParam) ;
		return 0 ;

	case WM_DESTROY:
		PostQuitMessage (0) ;
		return 0 ;
	}
	return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
}

void DrawRectangle (HWND hwnd)
{
	HBRUSH hBrush ;
	HDC    hdc ;
	RECT   rect ;

	if (cxClient == 0 || cyClient == 0)
		return ;

	SetRect (&rect, rand () % cxClient, rand () % cyClient,
		rand () % cxClient, rand () % cyClient) ;

	hBrush = CreateSolidBrush (
		RGB (rand () % 256, rand () % 256, rand () % 256)) ;

	hdc = GetDC (hwnd) ;
	FillRect (hdc, &rect, hBrush) ;
	ReleaseDC (hwnd, hdc) ;
	DeleteObject (hBrush) ;
}     
